During an injection molding operation performed using a plastic material, shrinkage rate and warpage rate are critical variables, which can be predicted from the relationship among pressure (P), specific volume (V), and temperature (T) (known as the PVT properties) of the plastic material.
Normally, when measuring the PVT properties of the plastic material, the volumetric variation of the plastic material is measured under isobaric or isothermal conditions provided by a measuring apparatus.
During a conventional measuring process, the plastic material may lack uniformity of density due to non-uniform temperature distribution, and volumetric measurement errors may occur as a result. In addition, the plastic material may leak, or elements of the measuring apparatus may stick or rub against each other due to non-uniform temperature distribution.
This Discussion of the Background section is for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed in this section constitutes a prior art to the present disclosure, and no part of this section may be used as an admission that any part of this application, including this Discussion of the Background section, constitutes prior art to the present disclosure.